I know this will be considered a pointles exercise by, well by any one with sense but in a moment of idleness i did it any way.
Having made some flax linen char cloth I decided to see if I could make it easier to catch a spark. This was mainly because (a) I had some spare (b) it seemed remarkably strong, (c) I had the dregs of a strong potasium nitrate solution in a jam jar and (d) the linen rope I turned into slow match takes a lot better spark than just the charred rope.
I've dunked a dozen or so pieces in the liquid and dried them on a tin tray. They didn't come apart and when we get a day when it's suitable outside I will try a comparitive test with the undoctored stuff.